**Question:** HHV-8 causes -

A. Kaposi's sarcoma
B. Cytomegalic infection
C. Epstein-Barr virus infection
D. Human immunodeficiency virus infection

**Core Concept:** Human Herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV), is a virus that belongs to the Betaherpesvirus subfamily. It is closely related to EBV (Epstein-Barr virus) and is known to cause various pathological conditions.

**Why the Correct Answer is Right:** HHV-8 is primarily responsible for Kaposi's sarcoma (Kaposi's sarcoma-associated herpesvirus, KSHV, is a misnomer). Kaposi's sarcoma is a type of tumor that mainly affects skin, but can also involve other organs. The virus enters host cells by binding to receptors like CD30, CD4, and CD26, which facilitates viral entry and integration into the host genome. KSHV can cause both primary infection and latency, thereby contributing to the pathogenesis of various conditions, including Kaposi's sarcoma.

**Why Each Wrong Option is Incorrect:**

A. Kaposi's sarcoma is primarily caused by HHV-8 (KSHV), not Cytomegalic infection.

B. Human immunodeficiency virus (HIV) infection is caused by HIV, not HHV-8. While both viruses can lead to immune compromise, they are distinct and cause different diseases.

C. Epstein-Barr virus (EBV) is responsible for infectious mononucleosis and certain lymphomas, but not Kaposi's sarcoma, which is caused by HHV-8.

**Clinical Pearl:**

HHV-8 is associated with three main clinical entities:
1. Kaposi's sarcoma: The most common manifestation, particularly in HIV-infected patients.
2. Primary effusion lymphoma (PEL): A rare lymphoma type that primarily affects the body cavities.
3. Multicentric Castleman disease: A lymphoproliferative disorder characterized by enlarged lymph nodes and involvement of other organs.

**Correct Answer Explanation:** Kaposi's sarcoma is the primary disease caused by HHV-8, also known as KSHV (Kaposi's Sarcoma-Associated Herpesvirus). This explains why options A, B, and C are incorrect.